WE’VE been following along with the build of Arby’s POR440 Valiant hardtop for a while now. It’s got a stock 5.3-litre LS-style truck motor with an 80mm BorgWarner turbo, and Arby wants to see eight-second timeslips from this relatively low-buck combo.

The 1970 VG Val has been fitted out with all the goodies from Haltech, including an Elite 2500 ECU, IQ3 digital dash and exhaust gas pyrometers for every cylinder. They’ve got ECU datalogging inputs for everything from transmission temp through to radiator coolant pressure. The idea behind monitoring the coolant pressure is that if the ECU detects a spike in the coolant – from a head gasket failure for example – it can shut the engine down before things get catastrophic. Using exhaust gas pyrometers is great for tuning each individual cylinder to perfection.

With the plan to run this car at Street Machine Drag Challenge, the boys have gutted the interior and welded in an eight-point rollcage with removable intrusion bars. Arby has added some venetian blinds to hide the ’cage, and there’s a pair of 235 M&H drag radials tucked under the bum.

On the dyno, with 14psi boost, the little 5.3 delivered 480hp to the back tyres on premium 98-octane fuel. Not a bad start. Next the guys decided to up the ante with E85 and crank up the boost. At 20psi the combo was making 610rwhp with bugger-all timing. At that point they discovered the plug gap was getting too large for the spark, and with the hour getting late they decided that was good enough. Until it wasn’t.

A couple of days later they decided to re-gap the plugs and put some timing in the combo. This saw power climb to around 700rwhp, and then it started to lift the heads. So they pulled the heads, replaced the gaskets with good multi-layer units and checked the heads for flatness. Then with everything back together they headed to Sydney Dragway to see what it would run; that’s the subject of the next video. In the meantime, watch the guys pull an all-nighter to see an easy 610rwhp from the budget Valiant. Stay tuned for the next instalment.